A method and device for creating an accurate simulation or model of the performance of a vehicle or an internal combustion engine in accordance with the invention comprises accessing the engine on-board diagnostic port (OBD), reading data from the desired industry standard parameter indicators (PID), using these data to produce a basic simulation of the engine operating characteristics, accessing and reading non-industry standard PIDs and using the output from the basic simulation in order to identify the non-industry standard PIDs with a high degree of certainty. As it may not be possible to identify some or all of the required non-industry standard PIDs or their scale due to timing delays or coding, an additional feature of the invention is to prompt a driver of a vehicle to drive the vehicle in a certain way or to perform a certain operation of the engine in order to trigger an event which will assist in identifying the missing non-industry standard PID(s) or will increase the degree of correlation or certainty in identifying the function or the scale of the said non-industry standard PID.